A ruthenium-catalyzed oxidative dearomatization of 2-alkyl- or 2-aryl-substituted
indoles has been developed. When coupled with a cascade transformation, it provides
a new system for the construction of indolin-3-ones bearing a C2-quaternary functionality.
The reaction occurs readily with RuCl3·3H2O as a catalyst in acetonitrile. 2-(3-Indolyl)-substituted indolin-3-ones were obtained
in medium to high yields. A mechanism for the reaction is also proposed.
Key words
ruthenium catalysis - oxidation - dearomatization - indoles - indolinones